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Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory Rate Constant Estimation for Large Chemical Kinetic Models and Application to Biofuels CC 2001 ICCK 2001, MIT July 28, 2011 William J. Pitz, Henry J. Curran, Charles Westbrook, Marco Mehl, S. M. Sarathy and Taku Tsujimura Sarathy and Taku Tsujimura Lawrence Livermore National Laboratory LLNL-PRES-490531 Lawrence Livermore National Laboratory, P. O. Box 808, Livermore, CA 94551 This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Transcript
Page 1: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Lawrence Livermore National LaboratoryLawrence Livermore National Laboratory

Rate Constant Estimation for Large Chemical Kinetic Models and Application to Biofuels

CC 2001ICCK 2001 MITJuly 28 2011

William J Pitz Henry J Curran Charles Westbrook Marco Mehl S MSarathy and Taku TsujimuraSarathy and Taku Tsujimura

Lawrence Livermore National Laboratory

LLNL-PRES-490531

Lawrence Livermore National Laboratory P O Box 808 Livermore CA 94551This work performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344

Development of chemical kinetic models for fuels

Ab initio calculationsFundamental experimental measurementsmeasurements

oh 713 0 rucich 1o 1 0 0g 300000 5000000 1710000 01

285376040e+00 102994334e-03-232666477e-07 193750704e-11-315759847e-16 2

369949720e+03 578756825e+00 341896226e+00 319255801e-04-308292717e-07 3

364407494e-10-100195479e-13 345264448e+03 254433372e+00 4c3h8+ohlt=gtnc3h7+h2o 1054e+10 0970 1586e+03

Detailed chemical kinetic Reaction rate rules

C1C2 base chemistry Thermodynamic database Reaction rate constants

model for practical fuelsReaction rate rules

High temperature mechanismReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerization

reactions

h+o2lt=gto+oh 965E+14 -0262 162E+04

o+h2lt=gth+oh 5080e+04 2670 6292e+03

oh+h2lt=gth+h2o 2160e+08 1510 3430e+03

o+h2olt=gtoh+oh 2970e+06 2020 1340e+04

h2+mlt=gth+h+m 4577e+19 -1400 1044e+05

h2 2 5 h2 12 1 9 2 3 8

2LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionReaction class 9 Olefin decomposition

h2 25 h2o 12 co 19 co2 38

o+o+mlt=gto2+m 6165e+15 -0500 0000e+00

h2 25 h2o 12 ar 83 co 19 co2 38 ch4 2 c2h6 3 he 83

o+h+mlt=gtoh+m 4714e+18 -1000 0000e+00

h2 25 h2o 12 ar 75 co 15 co2 2 ch4 2 c2h6 3 he 75

Need reaction rate rules for many chemical classes of fuels

AlkanesAlk Alkenes

Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species

OH

bull Alkylhydroperoxidesbull Alkylperoxy

OOH

3LLNL-PRES-490531

Lawrence Livermore National Laboratory

Need reaction rate rules for many types of reaction steps

HRbull

- RH

Fast High

Temperature CombustionLong Chain Alkanes

bull

ty

bull

+ O2OObull

Low T

Mechanism

Rea

ctiv

it Hi T

MechanismNTC

OO

OOHbull

Mechanism

+ HO2bull

O

Reactor TemperatureOOH

+ O2

+ bullOH

+ bullOH+

O

Degenerate Branching Path

bullOO

O- bullOH

O OH

4LLNL-PRES-490531

Lawrence Livermore National Laboratory

HOOO

bull

bullOH+ +

Assign reaction rate rules by reaction classes

High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition

5LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 2: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Development of chemical kinetic models for fuels

Ab initio calculationsFundamental experimental measurementsmeasurements

oh 713 0 rucich 1o 1 0 0g 300000 5000000 1710000 01

285376040e+00 102994334e-03-232666477e-07 193750704e-11-315759847e-16 2

369949720e+03 578756825e+00 341896226e+00 319255801e-04-308292717e-07 3

364407494e-10-100195479e-13 345264448e+03 254433372e+00 4c3h8+ohlt=gtnc3h7+h2o 1054e+10 0970 1586e+03

Detailed chemical kinetic Reaction rate rules

C1C2 base chemistry Thermodynamic database Reaction rate constants

model for practical fuelsReaction rate rules

High temperature mechanismReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerization

reactions

h+o2lt=gto+oh 965E+14 -0262 162E+04

o+h2lt=gth+oh 5080e+04 2670 6292e+03

oh+h2lt=gth+h2o 2160e+08 1510 3430e+03

o+h2olt=gtoh+oh 2970e+06 2020 1340e+04

h2+mlt=gth+h+m 4577e+19 -1400 1044e+05

h2 2 5 h2 12 1 9 2 3 8

2LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionReaction class 9 Olefin decomposition

h2 25 h2o 12 co 19 co2 38

o+o+mlt=gto2+m 6165e+15 -0500 0000e+00

h2 25 h2o 12 ar 83 co 19 co2 38 ch4 2 c2h6 3 he 83

o+h+mlt=gtoh+m 4714e+18 -1000 0000e+00

h2 25 h2o 12 ar 75 co 15 co2 2 ch4 2 c2h6 3 he 75

Need reaction rate rules for many chemical classes of fuels

AlkanesAlk Alkenes

Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species

OH

bull Alkylhydroperoxidesbull Alkylperoxy

OOH

3LLNL-PRES-490531

Lawrence Livermore National Laboratory

Need reaction rate rules for many types of reaction steps

HRbull

- RH

Fast High

Temperature CombustionLong Chain Alkanes

bull

ty

bull

+ O2OObull

Low T

Mechanism

Rea

ctiv

it Hi T

MechanismNTC

OO

OOHbull

Mechanism

+ HO2bull

O

Reactor TemperatureOOH

+ O2

+ bullOH

+ bullOH+

O

Degenerate Branching Path

bullOO

O- bullOH

O OH

4LLNL-PRES-490531

Lawrence Livermore National Laboratory

HOOO

bull

bullOH+ +

Assign reaction rate rules by reaction classes

High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition

5LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 3: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Need reaction rate rules for many chemical classes of fuels

AlkanesAlk Alkenes

Cycloalkanes Aromatics Aromatics Alcohols Methyl esters (biodiesel compounds)y ( p ) Carbenes (aldehydes ketenes) Special structures in intermediate species

OH

bull Alkylhydroperoxidesbull Alkylperoxy

OOH

3LLNL-PRES-490531

Lawrence Livermore National Laboratory

Need reaction rate rules for many types of reaction steps

HRbull

- RH

Fast High

Temperature CombustionLong Chain Alkanes

bull

ty

bull

+ O2OObull

Low T

Mechanism

Rea

ctiv

it Hi T

MechanismNTC

OO

OOHbull

Mechanism

+ HO2bull

O

Reactor TemperatureOOH

+ O2

+ bullOH

+ bullOH+

O

Degenerate Branching Path

bullOO

O- bullOH

O OH

4LLNL-PRES-490531

Lawrence Livermore National Laboratory

HOOO

bull

bullOH+ +

Assign reaction rate rules by reaction classes

High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition

5LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 4: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Need reaction rate rules for many types of reaction steps

HRbull

- RH

Fast High

Temperature CombustionLong Chain Alkanes

bull

ty

bull

+ O2OObull

Low T

Mechanism

Rea

ctiv

it Hi T

MechanismNTC

OO

OOHbull

Mechanism

+ HO2bull

O

Reactor TemperatureOOH

+ O2

+ bullOH

+ bullOH+

O

Degenerate Branching Path

bullOO

O- bullOH

O OH

4LLNL-PRES-490531

Lawrence Livermore National Laboratory

HOOO

bull

bullOH+ +

Assign reaction rate rules by reaction classes

High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition

5LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 5: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Assign reaction rate rules by reaction classes

High temperature mechanismR ti l 1 U i l l f l d itiReaction class 1 Unimolecular fuel decompositionReaction class 2 H atom abstractions from fuelReaction class 3 Alkyl radical decompositionReaction class 4 Alkyl radical + O2 = olefin + HO2Reaction class 5 Alkyl radical isomerizationReaction class 6 H atom abstraction from olefinsReaction class 6 H atom abstraction from olefinsReaction class 7 Addition of radical species to olefinsReaction class 8 Alkenyl radical decompositionR ti l 9 Ol fi d itiReaction class 9 Olefin decomposition

5LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 6: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Reaction classes for low temperature reactionsLow temperature mechanismReaction class 10 Alkyl radical addition to O2 (R + O2)Reaction class 11 R + RrsquoO2 = RO + RrsquoOReaction class 11 R R O2 RO R OReaction class 12 Alkylperoxy radical isomerizationReaction class 13 RO2 + HO2 = ROOH + O2Reaction class 14 RO2 + H2O2 = ROOH + HO2R ti l 15 RO + CH O RO + CH O +OReaction class 15 RO2 + CH3O2 = RO + CH3O +O2Reaction class 16 RO2 + RrsquoO2 = RO + RrsquoO + O2Reaction class 17 ROOH = RO + OHReaction class 18 RO DecompositionpReaction class 19 QOOH = Cyclic Ether + OHReaction class 20 QOOH = Olefin + HO2Reaction class 21 QOOH = Olefin + Aldehyde or Carbonyl + OHReaction class 22 Addition of QOOH to molecular oxygen OReaction class 22 Addition of QOOH to molecular oxygen O2Reaction class 23 O2QOOH isomerization to carbonylhydroperoxide + OHReaction class 24 Carbonylhydroperoxide decompositionReaction class 25 Reactions of cyclic ethers with OH and HO2

6LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 7: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Reaction rate rules make the assignment of reaction rate constants manageable Class 2

H atom abstraction rate rules for alkanes

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 6 50 05 2 40 4 471

H- atom abstraction rate rules for alkanes

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 151E-01 365 7154

CH3 2 755E-01 346 5481

3 6 01E 10 6 36 8933 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

7LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 8: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Reaction rate rule issues fuel decomposition reactionsClass 1

AlkanesS t b ti

C-C-C-C lt=gt C + C-C-Cbull Set by reverse reaction

Exothermic directionC C bond breaking most important

C-C-C-C lt=gt C-C + C-C

C-C bond breaking most important Some variations in forward rate constants even

though you think they should be all the same

8LLNL-PRES-490531

Lawrence Livermore National Laboratory

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 9: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Reaction rate rules for H-atom abstraction from alkanesClass 2

C H A ( 3 l 1 1) E ( l)

Fuel + (H OH CH3 HO2) =gt fuel radical + (H2 H2O CH4 H2O2)

C-H type A (cm3 mol-1 s-1) n EA (cal)

1 222E+05 254 6756

H 2 650e+05 240 4471

3 602E+05 240 2583

1 176E+09 097 1586

OH 2 234E+07 161 -35

3 573E+10 051 63

1 1 51E 01 3 65 7 1541 151E-01 365 7154

CH3 2 755E-01 346 5481

3 601E-10 636 893

1 680E+00 359 17160

HO2 2 316E+01 337 13720

3 650E+02 301 12090

9LLNL-PRES-490531

Lawrence Livermore National Laboratory

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 10: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

1E-10

05 1 15 2 25 3 35 4 45

n-butane+oh = radical+h2o Class 2New Argonne data for OH + alkanes

Sirvaramakrishnan et al 2009 (Argonne)

n-butane + OH = butyl + H2O

1E-11Droege and Tully 1986 (Sandia)

LLNL-NUIG Reaction rate rules

1E-12

10LLNL-PRES-490531

Lawrence Livermore National Laboratory

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 11: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

h di l h

New measured and calculated rate constants for OH + alkanes are higher at T gt 900K Class 2

1 E ‐ 1 0

0 5 1 1 5 2 2 5 3 3 5 4 4 5

n‐propane+oh = radical+h2og

Si k i h 2009 i t

Sivaramakrishnan 2009 theory

1 E ‐ 1 1

LLNL‐NUIG reaction rate rule

Sivaramakrishnan 2009 experiments

Squares Droege and Tully 1986 experiments

Sirvaramakrishnan 2009

propane + OH = propyl + H2O

1 E ‐ 1 2

LLNL-NUIG rate rule (based on Tully)

11LLNL-PRES-490531

Lawrence Livermore National Laboratory

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 12: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

n propane+oh= radical+h2o

Ab initio calculations show higher rates due to higher primary rate Class 2

n‐propane+oh = radical+h2o

LLNL primaryLLNL d

Argonnersquos calculated cross-over

1E+13

sec‐1

LLNL secondaryArgonne primaryArgonne secondary

(ab initio)

(ab initio)

3 mole‐

1 ‐s

Tully primaryTully secondary

(Experimental)

(Experimental)

Tullyrsquos measured

k cm

3 Tully s measured crossover

1E+12propane + OH = propyl + H2O

12LLNL-PRES-490531

Lawrence Livermore National Laboratory

05 10 15 201000T[K]

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 13: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

H-atom abstraction from the fuel HO2 + alkanesUncertainty in rate of a factor of 3 - 6 Class 2

C3H8+HO2 =gt iC3H7+H2O2Ignition very

sensitive to this rate constant

NUIG

CSM under RCM conditions

13LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 14: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Fuel + HO2 shows high sensitivity when the fuel is hydrogen Class 2

H2O2+HH2+HO2Sensitivity results under conditions in rapid compression machine

20

25

30

[ms] Sensitivity Rate Constants x 2

H2O2+Hlt=gtH2+HO2BaselineH+O2lt=gtO+OHH+O2+Mlt=gtHO2+MH2O2+Mlt=gtOH+OH+MHO2+Hlt=gtOH+OHHO2+Hlt=gtH2+O2OH H2 H H2O

50 bar end of compressionphi=1H2O2N2Ar = 1256251812563125

Baseline New rate constant fit

10

15

Igni

tion

dela

y OH+H2lt=gtH+H2OO+H2lt=gtH+OHH2O2+Hlt=gtH2O+OHH2O2+OHlt=gtH2O+HO2HO2+HO2lt=gtH2O2+O2H2O2+Olt=gtOH+HO2

Most sensitive reaction1E+13

1E+14H2O2+H lt=gt H2+HO2 Baulch et al 2005

Tsang and Hampson 1986

Ellingson 2007

Temperature of Sensivity analysis

(963 K)New fit

0

5

094 096 098 100 102 104 106

1Tc [1K]

H2O2+Hlt=gtH2+HO2

1E+12

Log

k

Baldwin and Walker 1967

Fit new H2 mechanism

N t d t Elli 2007

1E+10

1E+11

05 07 09 11 13 15 17

New computed rate Ellingson 2007Important branching sequence at high pressure

H2+HO2=gtH+H2O2

H2O2=gtOH+OH

Retarding reaction

14LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T[K]Retarding reaction

HO2+HO2=gtH2O2+O2

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 15: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Class 3 alkyl radical decomposition Improvements for iso-octane Class 3

1000

10 atm100

mes

[ms]

10 atm

Stoichiometric mixtures

10

ion

Del

ay T

i

55 atm

1Igni

t

Dashed Previous mechanism on website

Solid Updated version01

08 09 1 11 12 13 14 15 16

Solid Updated version

15LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000KT

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 16: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

More accurate estimate for iso-octyl radical decomposition rate constant Class 3

1E+12

1E+13

LLNL originalC l d S h l f Mi b i iti

cC8H17 =gt tC4H9 + iC4H8

1E+09

1E+10

1E+11

k

Colorado School of Mines ab initio

Klippenstein ab initio

1E+06

1E+07

1E+08

Log

k

1E+03

1E+04

1E+05Milano generic for alkyl radicals

16LLNL-PRES-490531

Lawrence Livermore National Laboratory

06 08 10 12 14 16

1000T[K]

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 17: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Low temperature reactionsEffect of R-O2 bond strength varies with bond type and controls amount of low temperature chemistry

Class 10R+O2 RO2

Bond dissociation energy ( H ) R OO =gt R + O2

Values used in LLNL models

-10

-5

0

Bond dissociation energy ( H 298) R-OO =gt R + O2

-25

-20

-15

del H

-40

-35

-30

-45

17LLNL-PRES-490531

Lawrence Livermore National Laboratory

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 18: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Low temperature chemistry ROO QOOH isomerizations Class 12

O

6 Member ring isomerization

OO

OOH

OO

H

K6 = 25E+10 exp(-20450RT)

OO

OOHO

O

5 Member ring isomerization

O OOH

18LLNL-PRES-490531

Lawrence Livermore National Laboratory

K5 = 20E+11 exp(-26450RT)

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 19: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

RO2 isomerizations Rate constants from computational chemistry(Dean Carstensen et al Colorado School of Mines)

Class 12

5-member TS 6-member TSOH

OHR

tertiaryprimary

RO O

secondary

primarytertiary

Activation energy depends on ring size and overall thermochemistry Amenable to rule generation

19LLNL-PRES-490531

Lawrence Livermore National Laboratory

g

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 20: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Significant differences in CSM vs LLNL rate constants RO2 isomerization Class 12

bull CBS-QB3 results generally lower than LLNL values for 5-member TSbull CBS-QB3 results much higher than LLNL values for 6-member TS

ndash Mainly due to higher A-factors (much higher than alkyl i i ti )

20LLNL-PRES-490531

Lawrence Livermore National Laboratory

isomerizations)bull Differences lead to significantly different reaction pathways

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 21: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Mechanisms for fuels are built in a hierarchical manner and increase rapidly in size with fuel size

Hydrogen Methane8 Species - 20 Reactions 30 Species - 200 Reactions

Propane100 Species - 400 Reactions

CH4

CH3 O2

H2O2

OH

HO

HO

H2O

C H

3

CH3O

CH O

CH3OH

CH OH

2

C2H5

C2H6

C2H4

CH3OO

CH3OOH

HO2

HO2

H2O2 Aromatics

SootOH

HCO

CO

CO2

C2H3 CH2O CH2OHO2

C2H2

Soot CO2

21LLNL-PRES-490531

Lawrence Livermore National Laboratory

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 22: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Fuels Size and Mechanism Size

C H

n-Alkane Mechanism Size

(Detailed Mechanism)C8H18

C10H22

700 Species

3150 Reactions

(Detailed Mechanism)

C12H26

950 Species

4050 Reactions

1250 Species

C14H30

1250 Species

5150 Reactions

1650 Species

C16H34

5150 Reactions

2100 Species

22LLNL-PRES-490531

Lawrence Livermore National Laboratory

8150 Reactions

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 23: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Application of rules to biofuels

BiodieselL th l tbull Large methyl esters

Alcoholsbull Iso pentanolbull Iso-pentanolbull Butanol

Aromatics

Olefins

23LLNL-PRES-490531

Lawrence Livermore National Laboratory

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 24: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Biofuelsbull Biodieselbull New types of biofuelsNew types of biofuels

Biomass derived from algae and other single cell organisms

Algal pilot scale bioreactor in Lawrence Kansas

F S ith St d N ll d Billi T d E l E l (2010)

rapeseed

24LLNL-PRES-490531

Lawrence Livermore National Laboratory

From Smith Sturm deNoyelles and Billings Trends Ecol Evol (2010)

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 25: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Algal oil-derived fuels contain additional esters

From Marchese and B Fisher Measurement of Gaseous and Particulate Emissions from Algae-Based Fatty Acid Methyl Esters SAE 2010-01-1523

25LLNL-PRES-490531

Lawrence Livermore National Laboratory

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 26: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Soybean and rapeseed derived biodiesels have only 5 principal componentsp p p

Methyl Palmitate (C160)

triglycerideOO

O

O

R R

+ 3 CH 3OH

Fatty acid methyl esters (FAMEs)

Methyl Stearate (C180)

methanolO

O

O

R OHO

70

Methyl Oleate (C181)methyl ester glycerol

OHOH

CH3OR

3 +

3040506070

SoybeanRapeseed Methyl Linoleate (C182)

0102030

Methyl Linolenate (C183)

26LLNL-PRES-490531

Lawrence Livermore National Laboratory

C160 C180 C181 C182 C183

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 27: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Assembled chemical kinetic model for all of the five main components in biodiesel derived from soybeans or rapeseed oil

Built with the same reaction rate rules as our successful

th l d t d th l

methyl palmitate

methyl decanoate and methyl decenoate mechanismmethyl stearate

5 component mechanism

approximatelymethyl linoleate

methyl oleate

approximately

5000 species20000 reactions

methyl linoleate

methyl linolenatemethyl linolenate

27LLNL-PRES-490531

Lawrence Livermore National Laboratory

Model with all 5 components now published and availableWestbrook Naik Herbinet Pitz Mehl Sarathy and Curran Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels Combustion and Flame 2011

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 28: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Experimental validation New biodiesel model reproduces oxidation of n-decanemethyl palmitate mixture in jet stirred reactor

10 Methyl palmitate

0 6

08

on Stoichiometric fuelO2He

04

06

Con

vers

io

n-decane

Stoichiometric fuelO2He mixtures1 atm15 s residence time

02

Jet stirred reactor data H kk t l C b Fl00

500 600 700 800 900 1000 1100

Temperature - K

Hakka et al Comb Flame 2009

28LLNL-PRES-490531

Lawrence Livermore National Laboratory

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 29: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Many of the predicted species profiles compare well with experiments eg 1-heptene

80E-05

60E-05

on

1-heptene

Jet stirred reactor data

40E-05

Mol

e fr

actio Jet stirred reactor data

Hakka et al Comb Flame 2009

20E-05

M

00E+00500 600 700 800 900 1000 1100

Temperature - K

29LLNL-PRES-490531

Lawrence Livermore National Laboratory

Temperature K

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 30: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Biodiesel components ignite in order of number of double bonds

100 Engine-like diti

ms

stearate

linoleate

palmitate

conditions135 barStoichiometric fuelair mixtures

10

on d

elay

-m

oleate

linolenate

1

Igni

tio

0108 1 12 14 16

30LLNL-PRES-490531

Lawrence Livermore National Laboratory

1000T - K

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 31: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Increased number of double bonds reduces low T reactivity of individual components in stirred reactor at diesel conditions

methyl stearate CN101

Diesel engine conditions of high pressure and fuel-rich mixtures 50 bar =2 (Fuel 200 ppm residence time = 005 s)

1

Simulated conversions of biodiesel components

methyl stearate CN101

methyl oleate CN 59

06

08

rsio

n

St t 101

CN

C 23

methyl oleate CN 59CN101

CN 59

02

04

Con

ver Stearate 101

Oleate 59

Linolenate 23

CN 23

methyl linolenate

0500 600 700 800 900 1000 1100

Temperature - KD i d t b f K th (2010)

Jet stirred reactor

31LLNL-PRES-490531

Lawrence Livermore National Laboratory

Derived cetane numbers from Knothe (2010)

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 32: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

C = C double bonds reduce low T reactivity

s s a v v a s s- C ndash C ndash C ndash C = C ndash C ndash C ndash C -

s s a a s ss s a a s s

Inserting one C=C double bonds changes the reactivity g g yof 4 carbons atoms in the C chain

Allylic C ndash H bond sites are weaker than most others Therefore they are preferentially abstracted by radicals O2 is also very weakly bound at allylic sites and falls off

rapidly inhibiting low T reactivity

32LLNL-PRES-490531

Lawrence Livermore National Laboratory

rapidly inhibiting low T reactivity

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 33: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

We have seen the same effect in hydrocarbon fuels hexenes

Ignition delay times in a rapid compression machine of hexene isomers

80

100

[ms]

80

100

[ms]

machine of hexene isomers (086-109 MPa Φ=1)

C = C - C - C - C - C 1-hexene

3-Hexene

2-Hexene40

60

80

dela

y tim

e 3-Hexene

2-Hexene40

60

80

dela

y tim

e C - C = C - C - C - C 2-hexene

C - C - C = C - C - C 3-hexene

1-Hexene0

20

40

Igni

tion

d

1-Hexene0

20

40

Igni

tion

d

RO2 isomerization initiates low temperature reactivity

0650 700 750 800 850 900

T [K]

0650 700 750 800 850 900

T [K]Moving the double bond towards the center of the molecule ldquoblocksrdquo more RO2 kinetics Experimental data Vanhove et al PCI2005

Simulations Mehl Vanhove Pitz Ranzi Combustion

33LLNL-PRES-490531

Lawrence Livermore National Laboratory

and Flame 2008

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 34: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Plant and animal fat oils have different fatty acid profiles that affect reactivity in a diesel engine

palmitate 7 7 7 4 23 10 13 28 46 11 8 4

stearate 5 2 1 8 3 4 4 21 4 8 4 1stearate 5 2 1 8 3 4 4 21 4 8 4 1

oleate 19 13 19 49 20 38 72 47 40 49 25 60

linoleate 68 78 19 38 53 48 10 3 10 32 55 21linoleate 68 78 19 38 53 48 10 3 10 32 55 21

linolenate 1 0 54 1 1 0 1 1 0 0 8 14

CN 49 50 39 58 51 49 55 58 62 54 47 549 9 9 7

With models for all 5 major components we can now model all these types of biodiesel

34LLNL-PRES-490531

Lawrence Livermore National Laboratory

bull Not a surrogate model but a real biodiesel (B100) model

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 35: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Use Diesel PRF as a scale to compare reactivity of biodiesel compoundsp

50 bar=2Si l t d Di l PRF l i PSR

1

Diesel PRF mixtures

CN60

2fuel 200 ppm=005s

CN50Jet stirred reactor

(n-hexadecane and 2244688-heptamethylnonane)Simulated Diesel PRF scale in a PSR

05

075

nver

sion

CN50

CN40

CNCN20

CN40

0

025

500 600 700 800 900 1000 1100

Con CN60

CN20

500 600 700 800 900 1000 1100

Temperature - K

As CN increases reaction in PSR starts at lower temperatures and has a greater e tent of lo T comb stion

35LLNL-PRES-490531

Lawrence Livermore National Laboratory

has a greater extent of low T combustion

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 36: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Diesel PRF scale allows assessment of the reactivity of biodiesel from different sources

Biodiesel fuelsSimulated reactivity profiles for biodiesel fuels

08

1

onlinseedbeef tallowpeanut

CN60 (PRF)

Beef tallow (CN58)

04

06

Con

vers

io peanutolivesoyrapeseed

CN20(PRF)

Linseed (CN39)

(C )

0

02

500 600 700 800 900 1000 1100

Temperature K

pCN20CN60

Rapeseed (CN54)(PRF)(PRF)

Temperature - K

Jet stirred reactor

50 bar=2fuel 200 ppm

36LLNL-PRES-490531

Lawrence Livermore National Laboratory

Jet stirred reactor =005s

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 37: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Observations on reactivity of biodiesel fuels from different oils

Methyl ester fuels from different plant and animal fats and oils have different reactivitydifferent reactivity

Detailed composition of these biodiesel fuels determine their reactivityreactivity

Biggest factor for reactivity variability of biodiesel large methyl ester fuels is the number of C=C double bondsester fuels is the number of C=C double bonds

We can model kinetics of most of these biodiesel fuels using the new biodiesel kinetic mechanism

The mechanisms still need refinements and testing and careful

37LLNL-PRES-490531

Lawrence Livermore National Laboratory

laboratory experiments would be very valuable

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 38: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

What amp Why Isopentanol A Next Generation BioFuel Isopentanol (3-Methyl-1-Butanol or 3 Methylbutane-1-ol) is

one of biomass derived alcoholic fuel like Ethanol

httpwwwjbeiorg

The challenge of JBEI To convert all monomer sugars (hexoses and pentoses) released from depolymerization of

httpwwwjbeiorg

(hexoses and pentoses) released from depolymerization of lignocellulosic biomass into transportation fuels and other chemicals And the initial targets of JBEI is ethanol butanol isopentanol hexadecane and geranyl decanoate ester

Higher alcohols such as isopentanol has higher energydensity and lower hygroscopicity compared to ethanol

38LLNL-PRES-490531

Lawrence Livermore National Laboratory

density and lower hygroscopicity compared to ethanol Volatility is moderate like gasoline ldquoNotrdquo too high

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 39: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Approach

Development of Isopentanol reaction mechanismmechanism

Single-zone Simulations Validation

Study of the kinetics involved in the auto-ignition process

Si l t HCCI E i C b ti Simulate an HCCI Engine Combustion

Compare with representative experimental ltresults

39LLNL-PRES-490531

Lawrence Livermore National Laboratory

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 40: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Development of Reaction MechanismHigh temperature chemistry Unimolecular decomposition and H atom abstraction from fuel

by activated radicals mainly occur Alcohols have weak C-H bonds at siteL t t h i tLow temperature chemistry Based on low temp chemistry of isooctane because isooctane

has some similar structures to isopentanolhas some similar structures to isopentanol Results showed ldquoToo Short Ignition Delay amp Too Strong NTCrdquo

Concerted elimination of HO H

C

OO

O

Concerted elimination of HO2 Concerted elimination forming aldehyde

and HO2 from RO2 is so fast that low

40LLNL-PRES-490531

Lawrence Livermore National Laboratory

2 2

temperature reactions would be slowed down

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 41: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Schematic Energy Diagram for the Concerted Elimination of HO2

+ O2H abstraction by radicals

H + RadicalsOH

H

OH

+ Radicals

OOH

II O

OOH

+ HO2

I

O

IOO O

C

OH

O

41LLNL-PRES-490531

Lawrence Livermore National Laboratory

OH

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 42: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Validations of Reaction Mechanism100000

c]

05

Pi i 07 2 MPa

100000

c]

10

Pi i 07‐08

1000

10000

ay time [

se

ST‐Exp P 20MPa

CV‐Cal P 20MPa

RCM E P 2 0MP

Pini 07 2 MPa

1000

10000

ay time [

se

ST‐Exp P 23MPaCV Cal P 2 0MPa

Pini 07 08

2‐23 MPa

100

Ignitio

n de

la RCM‐Exp P 20MPa

RCM‐Cal P 20MPa

ST‐Exp P 07MPa

CV‐Cal P 07MPa

RCM E P 0 7MP

100

Ignitio

n de

la CV‐Cal P 20MPaRCM‐Exp P 20MPaRCM‐Cal P 20MPaST‐Exp P 07‐08MPaCV‐Cal P 08MPa

10

7 8 9 10 11 12 13 14 15

[ ]

RCM‐Exp P 07MPa

RCM‐Cal P 20MPa10

7 8 9 10 11 12 13 14 15

10 000T [1K]

RCM‐Exp P 07MPaRCM‐Cal P 07MPa

bull Isopentanol model developed in this study can reproduce the experimental data which were acquired under various T and P conditions with a shock tube and an RCM

10000T [1K] 10000T [1K]

42LLNL-PRES-490531

Lawrence Livermore National LaboratoryShock tube experiments Kenji Yasunaga Fiona Gillespie and Henry Curran (NUI Galway - Ireland)Rapid compression machine (RCM) experiments Bryan Weber Yu Zhang and Chih-Jen Sung (UConn)

tube and an RCM

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 43: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Developed chemical kinetic model for new biofuel iso-pentanol and compared it to experiments in Sandia HCCI engine p p g

Iso-pentanol mechanism

HCCI engine experimentsYang and Dec Sandia SAE 2010

N ti bi f l d b

Reaction rate rules on successful iso-

New generation biofuel proposed by DOE Joint BioEnergy Institute (JBEI)

Model development and application

octane because it has some similar structures

Model development and applicationLLNL visiting scientist

Dr Taku TsujimuraNational Institute of Advanced

43LLNL-PRES-490531

Lawrence Livermore National Laboratory

Industrial Science and Technology Japan

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 44: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Iso-pentanol model predicts correct combustion phasing as load is increased in Sandia HCCI engine g

Experiments and CalculationsRequired TBDC for constant combustion phasing

120

140

160

80

100

120

C[degC]

Exp CA10 368 6 deg CAwith EGR

Iso-pentanol

20

40

60

T BDC Exp CA10 3686 degCA

Cal CA50 3686 degCAExp CA10 3715 degCACal CA50 371 5 deg CA

m 038

0

80 100 120 140 160 180 200 220

P [kPa]

Cal CA50 3715 degCA

44LLNL-PRES-490531

Lawrence Livermore National Laboratory

Pin [kPa]

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 45: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Iso-pentanol model predicts intermediate heat release that allows high load operation for HCCI

E i t C l l ti

Iso-pentanol

Experiments

TDC

Calculations

TDC

CA10 3686 degCA

m 038

CA50 3686 degCAm 038m 038

no EGR

no EGR

HCCI engine experiments

45LLNL-PRES-490531

Lawrence Livermore National Laboratory

Yang and Dec Sandia SAE 2010

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 46: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Developed model for 4 isomers of butanol and compared model predictions to flame experiments at USCp p

Flame speed measurements

butanol mechanism 4 isomers

Flame speed measurementsEgolfopoulos et al USC

OH

Iso-butanol is a new type of

biofuel that can be made directly

Twin premixed counterflow flames

be made directly from cellulose using bacteria

46LLNL-PRES-490531

Lawrence Livermore National Laboratory

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 47: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Butanol mechanism accurately simulates flame speeds important for predicting spark ignition engine combustion Experimental data

Veloo Egolfopoulos et

40

50

60

ocity

(cms)

30

40

50

city (cms)

Veloo Egolfopoulos et al 2010 2011

fuelair mixtures

10

20

30

nar F

lame Velo

1‐Butanol10

20

30

ar Flame Velo

iso‐Butanol

1 atm

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lamin

Equivalence Ratio

30

40

50

elocity

(cms)

30

40locity (cms)

10

20

30

minar Flame Ve

2‐Butanol 10

20

inar Flame Ve

tert‐Butanol

47LLNL-PRES-490531

Lawrence Livermore National Laboratory

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

0

04 06 08 1 12 14 16 18

Lam

Equivalence Ratio

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 48: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Butanol model well predicts ignition delay times at pressures and temperatures found in IC engines

1Symbolsexperimental dataSung et al

Rapid compression machine

0 1s)

AIAA paper 2011iso-butanol

tert-butanol

01

ay ti

me

(s

Rapid compression machineU i it f C ti t

001

nitio

n D

ela University of Connecticut

n-butanol

2-butanolbutanol isomers

00011 05 1 15 1 25 1 35 1 45

Ign butanol isomers

15 atm phi=1 in air

48LLNL-PRES-490531

Lawrence Livermore National Laboratory

105 115 125 135 1451000T (1K)

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 49: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Chemical kinetic mechanism for larger aromatics

CO

CO

The kinetic mechanism of the aromatics has an intrinsic hierarchical structure

49LLNL-PRES-490531

Lawrence Livermore National Laboratory

CO2

H2OA new module specific to C8 alkyl aromatics is now under development

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 50: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

p-Xylene mechanism well reproduces species profiles in jet stirred reactor

1E‐02

1E‐01

O2

p-Xylene 1E‐04

1E‐03

Toluene

1 E‐05

1E‐04

1E‐03p Xylene

COCO2

1E‐05

1E 04

Benzaldehyde

Benzene

Cyclopentadiene

Mol

e Fr

actio

n

Mol

e Fr

actio

n1E‐06

1E‐05

900 1000 1100 1200 1300 1400T [K]

CH2O

1E‐06

900 1000 1100 1200 1300 1400T [K]

y

1E‐02Jet stirred reactor

Experiments Gail and DagautCombustion and Flame 2005

P = 1 atm Ф = 1 τ = 01s

ract

ion

1 E‐04

1E‐03

H2

CH4

C2H4

Mol

e Fr

1E‐05

1E 04 2 4

C2H6

C2H4

50LLNL-PRES-490531

Lawrence Livermore National LaboratoryT [K]

1E‐06

900 1000 1100 1200 1300 1400

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 51: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Ortho- para- and ethyl-benzene models compare well to ignition delay times measured at pressure and temperatures relevant to engines

100000

Ignition delay times in a shock tube for aromatics

10000

10 atm fuelair mixtures =1

Tim

es [micro

s]

Ortho xylene

1000

ion

Del

ay T

Ethylbenzene

Para-xyleneOrtho-xylene

Shock tube experimental data

10

100

Igni

t Shock tube experimental data Shen and Oehlschlaeger Combustion and Flame 2009

07 08 09 1

1000KT

51LLNL-PRES-490531

Lawrence Livermore National Laboratory

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 52: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Mechanisms are available on LLNL website and by email

httpwww-plsllnlgovurl=science_and_technology-chemistry-combustion

52LLNL-PRES-490531

Lawrence Livermore National LaboratoryLLNL-PRES -427942

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 53: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Summary

Reaction classes and reaction rate rules greatly simplify the task of developing chemical kinetic models andthe task of developing chemical kinetic models and assigning rate constants

Continually updating reaction rate rules and adding new y p g grules for new moieties such as those from new biofuels

Made a lot of progress in chemical kinetic modeling new classes of compounds like esters and alcohols andnew classes of compounds like esters and alcohols and difficult compounds to model like aromatics

53LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 54: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Acknowledgements

Fokion Egolfopoulos butanolJ ki S i t l Jackie Sung iso-pentanol

John Dec and Yi Yang iso-pentanol

54LLNL-PRES-490531

Lawrence Livermore National Laboratory

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory

Page 55: Lawrence Livermore National Laboratory Rate Constant ...web.mit.edu/icck/presentations/ICCK178oral.pdf · Development of chemical kinetic models for fuels Ab initio calculations Fundamental

Acknowledge support from

DOE Office of Vehicle TechnologiesG t Si hbull Gurpreet Singh

bull Kevin Stork

DOE Office of Basic Energy Sciencesbull Wade Sisk

DOD Office of Naval Research

55LLNL-PRES-490531

Lawrence Livermore National Laboratory


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